Such a turbine blade is known for example from WO 2005/003517 A1. The blade walls which form the blade airfoil enclose a cavity in which cooling air can flow. Furthermore, further passages for guiding a second medium, specifically fuel, are provided in the blade wall of the turbine blade. The cooling medium which flows inside the turbine blade can discharge outwards into a hot gas space through a plurality of through-holes which extend through the blade wall of the turbine blade. In order to produce a combustible mixture still in the blade wall, connecting lines are provided in this which connect the fuel-guiding passages to the through-holes. Therefore, fuel can be mixed with cooling air still inside the through-holes and can flow as a combustible mixture into the hot gas which flows around the turbine blade. With such a turbine blade, both the hot gas which flows through the turbine and the cooling air which flows out of the turbine blade can be reheated as a result of the combustion of the mixture, which in general is carried out for increasing the level of performance of the gas turbine, for reducing the pollutant emissions and for improving the efficiency of the gas turbine, and is known as a form of carnotization. This form of subsequent energy enrichment of the hot gas in the turbine is also known as “in-situ blade reheat”.
Furthermore, a combustion chamber with a multiplicity of porous heat-shield elements is known from WO 99/46540 A1, by means of which a combustible mixture can be subsequently introduced into the combustion space of a gas turbine, i.e. outside burners of the gas turbine.
A disadvantage in the case of the turbine blade which is known from the prior art relates to the production of the passages, of the chamber and of the outlet line if the turbine blade and its cavities are produced in the casting process. These cavities are to be produced comparatively expensively by means of mostly complex casting cores. For this purpose, a complexly structured casting core and/or casting shell corresponding to the desired cavity structure is required, which, however, are to be positioned securely and accurately in the casting device cost-intensively and only in a time-consuming manner so that when casting turbine blades with such complex structures an increased scrap rate ensues in most cases.
If on the other hand the cavities which are provided in the blade wall are produced by means of different coatings, then the masking of the uncoated rough components which is required for it is an especially time-consuming working step which leads to a prolonged and expensive production.